Question
Symbols 
can be written, whereas symbols 
are not acceptable. Answer Briefly.
Solution
The general convention of representing an element along with its atomic mass (A) and atomic number (Z) is 
. Thus, symbol 
is accrptable and
can be written but 
is not written. Since atomic number of an element is fixed, therefore it is not essential to indicate. However, mass number is not fixed or it depends upon the isotope taken. Hence it is essential to indicate mass number.
. Thus, symbol is accrptable and can be written but is not written. Since atomic number of an element is fixed, therefore it is not essential to indicate. However, mass number is not fixed or it depends upon the isotope taken. Hence it is essential to indicate mass number.
